Electrothermal protector.



PATENTED JAN. 22, 1907.

P.B,QO0K. BLEOTROTHERMAL PROTECTOR.

APPLICATION FILED APR.16,1906.

WITNESSES. mvaurom Wm M.

protectors adapted to protect electrical cirswitching the 0 FRANK B. 000K, or onrcaeo, ILLINOIS.

ELECTROTHEBMAL rior-zeros.

Specification. of Letters Patent.

Patented Jan. 22, 1907.

Application filed April16,1906l Serial Elo- 3ll,991.

To aZZ whom it may concern:

Be it known that I, FRANK B. Coon, a citizen of the United States of America, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Electrothermal Protector, of which the following is a specification, reference being had to the accompanying drawings, illustrating same.

My invention relates to electrothermal cuits and ap aratus from abnormally large currents of e ectricity, and especially to protectors adapted to protect from small increments of current above the normal, these currents being generally termed sneak currents. r

The principal objects of my invention are to provide simplicity of construction in such apparatus, to rovide improved meansfor jectionable current upon the operation of the protector, and to provide means for switching the current either direct or through a portion of the resistance of the heatin means. I

In t e protector of this invention 1 do not open the main circuit when the apparatus o crates, but simply switch the o ject'ionable current to another-path, preferably to earth, either direct or through a portion of the resistance of the protec or, the apparatus being adjustable to accomplish this end. It

is usually customary in protectors of this class to employ. a heat-susceptiblematerial, preferably a metallic solder, to secure certain operable portions together or against operatron under normal current conditions, this "due to the heat in the protector under absolder generally forming part of the electrical circuit through the protector. In my present invention 1 do not employ. any cementing .material whatsoever to hold the device against operatibn or in the circuit throu h the protector. .1 simply separate the switching portion from the protector by heat-susceptible insulating material which softens,

normal current conditions, and allows the switching portion to operate and switch the objectionable current to another path.

Referring to the accompanying drawings, illustrating the preferred form of my invention, Figure 1 is a side elevation of the protector of the invention with a portion thereof shown in cross-section. Fig. 2 is a right end elevation ol Fig. 1 with one supportingspring'removed. Fig. 3 shows a modified form of the invention in which the obj ectionable current is switched from the line direct to ground.

Like characters refer to like parts in the several figures.

Spring members 1, 2, and 3 are preferably mounted on a suitable base or support 4 The heating element 5, preferably a piece ol graphite or arbon, is held in fiace between the free en s of springs 1 am 2 thus completing the main circuit from conductor. 6, throughspring "1, l. ating element 5, and spring 2, to conductor 7. Each end of the heating element 5 may be provided with a recess 8, adapted to fit a projection on spring 1 or 2 to lirmly hold the element 5 in place against side pressure. The piece of graphite 5 is preferably firmly held inplace between springsl and 2, due to their tension, so as to Ina-lie good electrical connection therewith. The graphite 5 may be soldered to springs 1 and 2, if desired, in which case it is preferably metallically plated on its ends, so as to properly solder. v In case it is not soldered to springs 1 and 2 it may be readily and easily removed or replaced by another element 5 if damaged in any way.

The spring "member 3 is preferably the switching member and is p eferably connected to earth at 10. A piece of hcat-susceptible insulating material 11 is placed between the free end of spring 3 and the heat ing element 5, as shown in Fig. 2, so as to normally insulate spring 3 from 5. Spring 3 is normally under tension toward the element 5, and this tension securely holds the insulating member 11 in place. If this insulating member is softened or removed, the spring 3 will then come in. contact with the element 5, due to its own tension, and therei by make electrical connection therewith.

In Fig; 3 I have provided the heating element 5 with terminal caps 12 and "l, which are preferably soldered to the element 5 in the usual manner. The terminal caps 12 and 13 are preferably engaged with spring mem bers 14 and 1.5, respectively, in a well-known manner to securely mount the protector in operative position. The switching-spring 16 is arranged near one end of the protector to engage the elongated end. cap 13 when the protector is heated, and thereby establish a direct short circuit from conductor 6 to ground at 10. When this protector is used in connection with telephone-switchboard apparatus, conductor 6 is preferably conof element 5.

to ground through the entire resistance of g Y v 841,849

be reversed, however, if desired, in whic case the line cominginat 7 would be switched the heating element 5 of the protector. I

In Fig. 1 the switching-spring 3 may be ad; adjusted along the lengthof the heating element 5 so as to connect conductor 6 (or 7) to ground at 10 through any desired portion of the resistance 5. I

The operation of the device is as follows: When an abnormally large current of electricity traverses the heat-producing element 5 for a sufficient length .ofgtime, depending upon the strength of the current, it produces heat in 5, which heat softens the heat-susceptible material-11. When the material '11 is sulficiently softened, the spring member 3, due to its own, tension, presses the material 11 out from between itself and the element 5 and makes direct electrical connection with the element 5, thereby connecting the latter with the earth atlO and switchmg the objectionable current from one of the main circuit-springs 1 or 2H With the arrangement shown in Figs. 1 and. 2 the objectionable current is switched to earth through a portion of the resistance of 5, which portion can be regulated as desired by adjusting spring 3 along the length In 1 1g. 3, however, if the objectionuble current comes over conductor 6 it will beswitched direct to earth at 10, the entire resistance of heating element 5 and circuit being shunted out, and thereby protected from the objectionable current. I the objectionablecurrent comes from conductor 7, then it will be switched to earth at 10 through the entire resistancejof heatingv element 5. In either case, as in Figs. 1 and 2, either one or the other of conductors 6 or 7 will be protected from the objectionable current. i

When the abnormal current is removedi'rorn the circuit, the apparatus may beagain set for another operation by simply se arating spring 3 from the element 5 and p acing a new piece of heat-susceptible wax- 11 between the two. vill readily be seen that the protectorm operated over and over again as many times as desired, it only requiring a new piece of heat-susceptible material 11 after each operat'on.

' Ido not Wish to limit this invention to the exact details of construction as herein shown or to any particular heat-susceptible mate: rial for the portion 11: Many modifications may be made in the construction without departihg from the scope'of the iIlVGIltion or the principles involved. As a heatsusceptible insulating material 11 beeswax,

Japanese wax, shellac, palm-tree Wax, stearin, 7

l Vhat I claimas miy invention, and. desire to secure by Letters .atent, is, 1. An electrothermal protector comprising a heating element and having a switching member normally held therefrom by heatsusceptible insulating material and adapted ,to make electrical connection therewith upon heating.

2. An ele ctrothermal protector crimprising a heating element permanently held in cir- 7 5 cpit, means for groundinga ortioh of the circuit through a portion of t e heating element under abnormal cui rent conditions, and heat-susceptihle'insulating material norelectrical connection with tie heating. element.

3. An electrothermal p otector comprising a heating element permanently held in' cirmally holding th'efigroundin means out oi e cuit', means for switching a portion of the circuit oil through a portion of the heating ele-- ment, under abnormal current conditions,

and heat-susceptible insulating material normally holding the switching means away from the heating element.

4. Electrical protective apparatus com-i prising a air of s ring members,'a he'at-prm ducing cement eld between the s ring members by the tension thereof, a switc ing e ement under abnormalcurrent conditions,,-' and heat-susceptible insulating material nor- I mally holding the switching-spring member out of contact with the heating element. j 5. Electrical rotective a )paratu's comprising a pair 0 spring inem ers,- a heating eiement held in lace between the spring members, a switciing member arranged to make electrical connection with the heating element under abnormal current conditions so as to switch the objectionable current off through any desired portion of the heating element, and heat-susceptible insulating material normally holding the switching n1em her out of. electrical connection with the heat ing element.

6. Electrical protective apparatus comprising a pair of conducting members, a heatmg element permanently soldered in circuit with the conducting members, switchinfl means for making electrical connection with the heating element under abnormal 'current conditions, and heat-susceptible insulating material normally holding the switching means out of electrical connection with the heating element.

7. A heat-producing member normally held in the circuit whichiit isv to protects means for making electrica connection with,

the heat-producing member for establishing a circuit from the first-mentioned circuit'to ground, and heat-susce tible insulating material normally restraining the c cuit-estsblishing means from establishing tlie grounded circuit.

spring member adapted to engage the heating A heat-producing member normall metallic su held in the circuit which it 1s to protect, a to accoin. or; normally open cucurt from the heat-producgroundnu s and provided. will recesses the said points, means for n'cuit through a portion of '20 mg member to earth, adapted to be closed the heating cement, and heat-susceptible 5 under abnormal current conditions, and material non ally holding the grounding heatsusce" tible insulating material for normeans out of electrical connection with the mally holding the normally open circuit open heating eleme v.t. and arranged to be effected by the heat-pro- 1 1. A pair of metallic su ports, one bein 5 ducin member. a spring member and eaci being 1 rovideu to 9. g pair of spring members suitably with projecting point thereon, a lfeat-promounted and each provided with a projectducing member connected in circuit with the ing 'oint near the free end thereof, a heatmetallic supports and provided With recesses pro ucing element normally held between to accommodate the said points, means for 4.0 the said spring members near their free ends, switching a portion of the said circuit to an- 15 each end of the heating element being prol" path through a portion of the heatvided with a recess adapted to fit the said pi .ucing member under abnormal current projecting points, a circu1t-controlling spring conditions, and heat-susceptible material adapted to make electrical connection with normally holding the switching means from 5 the heating element under abnormal elecswitching the sald circuit.

20 trical conditions, and heat-susceptible insu- In; inventor of the foregoing I hereunto lating material normally holding he circuitsubscribe my name, in the presence of two controlling spring out of contact with the subscribing Witnesses,this.1 4th day of April,

heating element. 1906.

.10. A pair of metallic supports, one being FRANK B. CGOK. ":5 a s ring member and each being provided Witnesses:

wit. a projecting point thereon, a heat-pro- FREDERICK R, PARKER,

ducing member connected in circuit with the Emiun' N. STEPHENSON. 

